Not applicable.
Not applicable.
1. Technical Field
This invention relates in general to measuring devices and, more particularly, to an improved device for measuring roof rafter angles or other angles.
2. Description of Related Art.
Various measuring devices have been invented which provide a means to measure the angles of roof rafters and other types of angles which may occur in the construction industry. While many of those devices perform the required function of determining angles, those devices are normally cumbersome and complex. Such disadvantages are generally the result of designing a measuring device which is intended to work without taking advantage of the assistance that other tools may provide in measuring angles.
An example of this disadvantage is found in U. S. Pat. No. 4,712,307 for a rafter angle measuring device. That invention includes components which act as a framing square, ruler, and bubble level, as well as a rafter angle measuring device. Additionally, the invention includes a cumbersome arm which must be used to obtain a measurement of the angle of rafters. When not in use, the invention must be carefully folded and placed in a tool box for storage to ensure that the device is not damaged. The result of these characteristics is an invention which is cumbersome and which provides much more than is needed by a worker who simply wants to measure rafter angles or other types of angles.
U.S. Pat. No. 1,083,376 is another example of a measuring instrument that must work by itself to provide the worker with the measurement of rafter angles. This device also includes a number of capabilities other than the simple measurement of various angles and, as a result, the device is much more complex than it needs to be to simply measure angles.
Other measurement devices may be less cumbersome and less complex in design, yet fail to allow for the need to have long base lines to ensure that the measured angle is accurate. U.S. Pat. 4,742,619 discloses a roofing speed square for use in laying out and cutting roof rafters. However, the design of the device is intended to depend only upon the short adjacent sides of the device to establish the baseline for the angles being laid out and measured. Additionally, there is no provision for using the tool in conjunction with another device such as a large framing angle, to ensure that the base lines from which the angles are being measured are sufficient to guarantee angular accuracy. As a result, the invention suffers from being unable to provide accurate measurement of roof angles calculated from long base lines.
In each of these examples, the design of the measurement tool fails to provide an instrument which will allow the worker to measure rafter angles and other types of angles in a way which would permit the tool to be simple to use and which would allow the tool to be used in conjunction with another tool. Moreover, the designs of these tools do not permit the tools to be used in conjunction with another tool which could provide longer baselines for more accurate determination of angles.
Accordingly, it is an object of the invention to provide a measuring tool which is small and simple, and which can used with a standard framing square to allow a worker to measure and layout roof rafter angles and other types of angles.
It is yet another object of the invention to provide a measuring tool which, standing alone or in conjunction with a standard framing square, can be used to layout miter angles on materials which require angular cuts.
The present invention resides in a saddle protractor which can be used in conjunction with a standard framing square to measure rafter angles and other types of angles. Specifically, the invention discloses an angle measuring tool having angular graduations and which is designed to include various tabs which allow the tool to be securely engaged with the framing square. The saddle protractor includes a pivot pin or pivot tab which allows the device to be used as a miter layout device when used in conjunction with a framing square. One edge of the saddle protractor contains incremental graduations indicating angles in whole degree increments.